The invention relates to an undercarriage assembly for a motor vehicle, and furthermore relates to a method for producing an undercarriage assembly for a motor vehicle.
Design, technological, and material considerations for reducing the weight of undercarriage components are becoming increasingly important in light of efforts undertaken to reduce fuel consumption and emissions. Efforts are therefore made to provide lightweight yet strong undercarriage components such as front axle and rear axle supports. Ambitious dynamic strength requirements are currently being met by using either individual undercarriage components that are quite thick, or by employing lightweight materials that have the required strength. Since thick components are inconsistent with the objective of light weight, the current focus is on using strong, lightweight materials.
The 6000 aluminum alloy series that is primarily used for such components generally relates to those materials that can be hardened. In this material series, high strengths are attained using a special, multi-stage thermal treatment (T6=solution heat treated and aged). A yield point greater than 200 MPa is attained. However, this increase in strength is lost during the T6 tempering process in the area of the so-called heat affected zone. For instance, the yield point drops by approximately 60% to approximately 80 MPa in the heat affected zone. This decrease in strength, which is due to heat generated during the joining process, such as fusion welding, is currently compensated for by moving the weld seams to areas having a lower load. But this design may not be entirely feasible, or it may be completely impossible, or it may have to be compensated with commensurate increases in the cross-sections of the individual parts that are to be joined. Such measures further increase the weight of the individual parts. Even though the increased thickness would theoretically be necessary only for the short segments in the heat affected zone that lose strength due to the effects of heat, especially in the case of extrusion press profiles, the increased thickness normally runs the entire length of the component. Possible rivet or screw connections require prepared holes, and as a rule, also require access from the back side of the connection, which results in higher assembly costs. In series production, it is difficult to use adhesive connections for an undercarriage, both from a cost standpoint for preparing and executing the adhesive connection, and because the strength is sometimes inadequate. Heat-free joint connections also include so-called nail connections, as described in WO 2007/082714 A1.